Time measuring apparatus



Jan. 16, 1940. Q E, STAPLES 2,187,406

TIME MEASURING APPARATUS Original Filed March 13, v1935 2 Sheets-Sheet 1V T S 222 3g 1 5 L JF 1671 F 7 F 20 9 INVENTOR H15 ATTORNEY Jan. 16,1940. c, STAPLES 2,187,406

TIME MEASURING APPARATUS Original Filed March 13, 1935 2 Sheets-Sheet 2Time 60-- 20 40 60 50 Tfiam 5,09% [12 M RH.

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H15 ATTORN EY Patented Jan. 16, 1940 UNITED STATES PATENT OFFICE TIMENIEASURIN G APPARATUS Crawford E. Staples, Wilkinsburg, Pa., assignor toThe Union Switch & Signal Company, Swissvale, Pa., a corporation ofPennsylvania.

7 Claims.

My invention relates to time measuring apparatus, and particularly toelectrically operated time measuring apparatus.

A feature of my invention is the provision of novel and improved meansto actuate a circuit controlling contact member in accordance with thelapsed time of an event, such as, for example, the time required for arailway train to operate over a stretch of track. Other features andadvantage of my invention will appear as the specification progresses.

This application is a division of my application, Serial No. 16,869,filed March 13, 1935, for Apparatus for the control of highway crossingsignals, now Patent No. 2,089,919, granted August 10,1937.

I will describe one form of apparatus embodying my invention, and willthen point out the novel features thereof in claims.

In the accompanying drawings, Fig. l is a View partly diagrammatic andpartly in elevation of one form of apparatus that may be employed incarrying out the embodiment of my invention. Fig. 2 is a plan viewpartly diagrammatic of a portion of the apparatus of Fig. 1. Fig. 3 is adetail view of the biasing spring for the apparatus of Figs. 1 and 2.Figs. 4 and 5 are diagrams illustrating certain characteristics of theapparatus of Figs. 1, 2 and 3.

Similar reference characters refer to similar parts in each of theviews.

Although a particular application of apparatus embodying my invention ishere disclosed, it will be understood the invention is not limited tothis one application and many places will suggest themselves where timemeasuring apparatus embodying my invention will be useful.

Referring to. Fig. l, the reference characters i and l designate thetrack rails of a stretch of railway track over which traffic normallymoves in the direction indicated by an arrow and which stretch isintersected by a highway H. Two highway crossing signals Si and S2 arelocated adjacent the intersection and are indicated on the drawings bysymbols commonly used in the art to designate a flashing light highwaycrossing signal. As is common practice, these two signals are set forone to be plainly exhibited to highway traffic approaching the crossingin one direction and the other signal to be plainly exhibited to highwaytraflic approaching the crossing from the opposite direction.

As here shown, the track rails I and I are divided by the usualinsulated rail joints to form three track sections RS, S- I and T.-V,which sections are traversed successively in the order named by a trainapproaching the highway I-I when moving in the normal direction oftraffic. Each track section is provided with a track circuit comprisinga battery 3 connected across the track rails at one end of the sectionand a track relay designated by the reference character R plus anexponent corresponding to its location connected across the rails at theother end of the section. For the purpose of this description I shallrefer to the track section RS as a measuring section, section ST as anoperating section, and the section TV as a positive operating section.As will appear hereinafter, the speed of a train as it traverses themeasuring section R-S is measured, the highway signals Si and S2 are setinto operation in accordance with this measured speed after the trainhas entered the operating section 5-1 and positive operation of thesignals SI and S2 occurs during the time the train occupies the sectionT-V irrespective of whether it is moving or not.

In order to more easily understand the apparatus embodying my inventionI shall assume a maximum speed for all trains approaching the highway Hof miles-per hour. I shall also assume a time interval of 20 secondsexhibit of the highway signals before a slow moving train reaches theintersection and that this interval is uniformly increased as the speedbecomes greater until an exhibit of 30 seconds of the highway signalsfor a train traveling at the maximum speed of 60 miles per hour isprovided. I shall further assume the measuring section R-S to be 889feet in length, that is, the section RS is of such length that a trainmoving at the maximum speed of 60 miles per hour consumes approximately10 seconds in advancing therethrough. The combined lengths of theoperating section S-T and the positive operating section TV aresubstantially 2640 feet since a train traveling at the maximum speed of60 miles per hour moves 2640 feet in 30 seconds and, as above stated, a30 seconds exhibit of the highway crossing signals before a traintraveling at the maximum speed reaches the intersection is desired. Thesection T--V is preferably just long enough, say 200 feet, thatoperation of the highway crossing signals with a train occupying theintersection whether it is moving or not is assured. It follows thatwith the track arrangement here assumed the highway crossing signals S!-and S2 are set into operation for a train traveling at the maximum speedimmediately upon the train entering the'operating section S--T, but thatfor a train having a lower speed the starting of the .operation of thesignals SI and S2 is delayed after the train enters the operatingsection ST, this delay being such that the period of oper-- ation of thehighway signals before a train reaches the intersection becomesproportionally less as the speed becomes lower until at a speed of 20miles per hour the period of operation is only 20' seconds whereas atthe maximum speed the period of operation is 30 seconds. For speedslower than 20 miles per hour the period of oper ation remainssubstantially constant at 20 seconds. It will be understood, of course;that my invention is not limited to the above-stated Values of speeds,lengths of track sections and operating intervals of the highwaycrossing signals, and such values may be selected best suited for thelocation at which the apparatus is installed.

The operation of the signals SI and S2 is gov erned by anoperating unithere shown as an oscillator or code transmitter designated as a whole bythe reference character CT. This oscillator CT may take different formsbut a preferred form is that described and claimed in Letters Patent No.1,858,876, granted May 17, 1932, to Paul N. Bossart, for Codingapparatus. It is deemed'sufficient for the present application to givebut a brief description of this oscillator CT. A magnetic fieldstructure 5 has mounted between its two poles PI and P2 a spindle 8 onwhich an armature 6 is fixed so as to swing freely between the polepieces. The armature 6 and the spindle 8 are normally biased to theposition illustrated in Fig. 1 by any convenient biasing means such as acoil spring not shown, and the armature 6 is adapted to be attractedtoward the pole pieces of the field structure in response to a magneticfield created therein. As indicated schematically by dotted lines, threecam members 9, I0 and II are fixed on the spindle 8. These cam members9, I0 and II are each effective when rotated with the spindle 8 in amanner to shortly appear, to actuate a pair of circuit controllingcontact fingers. A field winding I is mounted on the field structure 5and is provided with a plurality of energizing circuits all of whichinclude the pair of contact fingers actuated by the cam member II. Whenthe relay R is deenergized and its back contact I2 is closed, a circuitis completed which extends from the B terminal of any convenient sourceof current such as a battery, not shown, over wire l3, back contact I2of relay R wire I4, winding I, contact I5-I6 actuated by the cam II andthence to the opposite terminal C of the same source of current. In theevent the track relay E is shunted and its back contact I! is closed, orif the track relay R is shunted and its back contact I8 is closed, acircuit extends from the B battery terminal over the back contact ll ofrelay R or over the back contact I8 of the relay R wire I4, winding I,contact I5I6. and to the C battery terminal. It follows that as long asany one of the track relays R R and R is shunted, the field winding I issupplied with current. but that when all three of these relays arepicked up the winding I is without current. With the winding I energizedand a magnetic field created in the field structure 5, the armature 6 isattracted toward the pole pieces and the spindle 8 is rotated in acounterclockwise direction against the force of the bias. After a slightmovement of the armature 6 in the counterclockwise direction, the cammember II actuates the contact finger I5 out of engage- I ment with thecontact finger I6 and the circuit connection therethrough is broken withthe result that the field winding I is deenergized. The

armature 6 rotates a little farther and then its movement is reverseddue to the bias and it swings clockwise toward its normal position. Thecam member II is now rotated back toward its normal position and thecontact I5I6 is again closed and the winding 1 is reenergized. Armature6 swings clockwise slightly past its normal position due to the inertiaof its parts and it is then again rotated in a counterclockwisedirection due to the influence of the magnetic field.

Consequently, as long as any one of the track relays R R or R is shuntedand the field winding I is supplied with current, the armature 6oscillates at its natural period, the period of oscillation beingdetermined by the bias and the weight of the parts. Although the periodof oscillation may be any convenient frequency, I shall consider it tobe 30 cycles per minute.

As stated above, the cam members 9 and III are fixed on the spindle 8,and hence the cam members 9 and I0 are rotated in response to theoperation of armature 6. The cam member 9 is so shaped that when rotatedcounterclockwise the associated contact fingers I9 and 20 are forcedapart to break engagement and open the circuit connection therethrough,but that when rotated in the clockwise direction within the limits ofthe movement of the armature 6, the contact fingers I9 and 20 remain inengagement to close the circuit connection therethrough. The cam memberI0 is so shaped that when rotated clockwise the associated contactfingers 2! and 22 are forced apart to open the circuit connectiontherethrough but when rotated in the counterclockwise direction withinthe limits of the movement of the armature 6, the contact fingers 2| and22 remain in engagement. It follows that as the armature 6. is rotatedcounterclockwise the contact I9--2Il is opened and as the armature 6swings clockwise past its normal position the contact 2I-22 is opened,but that at all other times these two contacts are closed.

The contacts I920 and 2 I -22 govern the circuits for lighting the lampsof the highway crossing signals SI and S2. With positive currentsupplied to the wire 23 in a manner to subsequently appear, currentfiows thence through contact Ill-20 over wire 24, lamp 25 of signal SIand to the negative terminal C of the. source of current. Branching fromthe wire 24 the cur- I rent flows over a circuit includingwire I5, lamp26of signal S2 and to the negative terminal C of the current source.Current also flows from wire 23 through the contact 2I--22 and thenceover wire 21 and the lamps 28 and 29 of signals SI and S2, respectively,in parallel and to the negative terminal C of the current source. It isto be seen, therefore, that with positive current supplied to the wire23 and the oscillator CT inactive, both lamps of each signal SI and Si!are steadily illuminated, but that with the oscillator operated in themanner explained and the contacts 19-20 and 2l-22 alternately opened andclosed, the lamps 25 and 28 of signalSI and the lamps 26 and 29 ofsignal S2 are alternately fiashed, the rate at which the signals areflashed being substantially 30 times per'minute since the frequency ofthe oscillator CT is 30 cycles per minute.

The oscillator CT in addition to governing the operation of the highwaycrossing signals SI and S2 in the manner just described, also actuates atime measuring mechanism effective to determine the speed of the trainapproaching the highway H and by which mechanism the time of starting ofthe operation of the signals S! and S2 before the train reaches theintersection is governed. I shall now describe this time measuringmechanism which is designated as a whole by the reference character TE.A worm 3!! is rigidly mounted on the spindle 3 and rocks a lever 3!pivoted at 32 and on which lever a pawl 33 is pinned for engaging with aratchet gear 34 with the result liig. 2 against the force of the spring41.

that-the ratchet gear 34 is rotated clockwise as viewed'in Fig. l, inresponse to oscillations of the armature 6 of the oscillator CT. A latch35 holds the ratchet gear 34 on the return stroke of the pawl 33. 36journaled at 3'1 and 38 (see Fig. 2). 39 and a cam are loosely mountedon the shaft 35 between the bearings 31 and 38, and between the gear 3%and the cam 40 a clutch member 4! and two springs 42 and 43 areprovided. The clutch member 4! is secured to the shaft 36 by a featherkey not shown, and hence, it rotates with the shaft 36 and may be movedalong the shaft toward either the gear 33 or toward the cam 4c. Theforkedv end of a lever 44 pinned at 45 rides in a slot 46 of the clutchmember 4!. The lever 46 is biased upward as viewed in Fig. 2 by a spring4'7 and is in magnetic relationship with an electromagnet 48, thearrangement being such that the magnet 48 when energized is effective todraw the lever 44 downward as viewed in It is to be seen, therefore,that magnet 48 when .en-

' ergized is effective to move the clutch member 4! and spring 43 intofrictional engagement with the cam 4% whereby the cam 46 is made torotate clockwise in response to clockwise movement of the ratchet gear34, but that magnet 48 when deenergized permits the spring 4'! to drawthe lever 44 upward and move the clutch member 4! out of engagement withthe cam 46 and into engagement with the gear 33 through the spring 472and that gear is rotated clockwise in response to clockwise movement ofthe ratchet year 34. In other words, the cam 46 is rotated clockwise inresponse to operation of the oscillator CT and ratchet gear 34 when theclutch magnet 48 is energized but is left free to turn on the shaft 36when the clutch magnet 48 is deenergized, whereas the gear 322 isrotated clockwise in response to operation of the oscillator CT andratchet gear 34 when the magnet 48 is deenergized and is left free toturn on the shaft 36 when the magnet -58 is energized. The cam 46 isprovided with a counterweight H and is so proportioned that it isimmediately restored to its normal position, that is, to the positionillustrated in Fig. 1, whenever the clutch magnet 48 is deenergized.

The gear 33 meshes with a gear 49 keyed to a shaft at which is journaledat 5! and 52 and on which shaft is keyed a restoring cam 53. Astationary spring case 54 has contained therein a coiled spring t5 (seeFig. 3) which is secured to the shaft 513 as well as to the case 54. Thespring 55 isefiective to bias the shaft 56 in the clockwise direction.Consequently, when the gear 39 is coupled to the shaft 36 through theclutch member 4! is rotated clockwise, the gear, shaft 5% and cam 53 arerotated counterclockwise "against the force of the spring 55 except whenthe mutilated portion 10 of gear 49 is adjacent the gear 38.Furthermore, when the gear 39 is rel ased from the shaft 33 the spring55 is effective to rotate theshaft-SO. and cam- 53 clockwise The ratchetgear 34 is keyed to a shaft A gear unless the cam 53 is restrained byother means in a manner to later appear.

The cams 4!] and 53 are utilized to operate a circuit contactcontrolling member or element and here shown as an arm 56. The arm 56 ispivoted at 5! and is provided with cam followers 58 and 59 positioned toride on the cams 40 and 53, respectively. A contact finger 60 is securedto the arm 56 by proper insulation and this contact finger 60 makesengagement with a stationary contact 6! when the arm 56 occupies thenormal" position, that is, the position illustrated by solid lines inFig. 1, but breaks engagement with the contact 6! as soon as the arm 56is rotated upward about its pivot 51. An armature 62 of suitablemagnetic material and a second contact finger 63 are also secured to thearm 56, the contact finger 63 being properly insulated from the arm. Anelectromagnet 64 is located for magnetic relationship with the armature62 when the arm 56 is rotated upward to a reverse position illustratedby the dotted lines in Fig. 1, and on the casing of the magnet 64 astationary contact 55 is secured for making engagement with the contactfinger 63 when the arm 56 is moved to its reverse position. The functionof the magnet 64 and the contacts 666! and 6365 will appear when theoperation of the apparatus is described.

In describing the operation of the apparatus, I shall assume the tracksections R,-S, 5-1 and T-V are unoccupied and the respective trackrelays are picked up so that the oscillator CT is inactive, the magnet48 is energized, and the lamps of the highway crossing signals S! and S2are all dark. Furthermore, I shall assume the cams 4t and 53 and the arm55 occupy their normal positions, that is, the positions illustrated inthe drawings. It is to be noted that in this normal position of theapparatus, the magnet 48 is supplied with current from the B terminal ofthe current source over front contact 66 of relay R front contact fi'lof relay R wire 68, winding of the magnet 48 and to the oppositeterminal C of the current source, and the magnet 48 is energized toattract the lever 44 and draw the clutch member 4i into engagement withthe cam 46. A train approaching the highway H from the right andentering the measuring section B shunts the track relay R and its backcontact !2 is closed with the result that current is supplied to thefield winding of the oscillator CT and the armature 6 is set intooperation. Although the cam members 9 and It! are operated to actuatethe contacts !926 and 21-22 the lamps of the highway crossing signals S!and S2 remain dark since the wire 23 is connected to a back contact 69of the magnet 48 and that magnet is now energized and its back contact69 is open. Operation of the oscillator CT at this time causes, however,the ratchet gear 34 to be rotated, and hence the cam 46 is movedclockwise since the magnet 48 is energized and the clutch member 4! isin frictional engagement with the cam 46. In the event this train I haveassumed to be approaching the highway H is traveling atthe maximum speedof 60 miles per hour, it consumes approximately 10 seconds in advancingthrough the measuring section R-S and entering the operating section S-Twhere it shunts the track relay R The cam 46 is so shaped that itsmovement caused by the first 10 seconds of operation of the oscillatorCT effects no upward movement of the arm 56 and. consequently, thecontact 666! is still closed when the train enters the section S- -T.That is 4- is an arc of a circle, the center of which is the center ofshaft 36. The shunting of the track relay R and'the closing of its backcontact I l continues the supply of current to the field winding l ofthe oscillator or, with the result that the oscillator continues tooperate as long as the train occupies the section ST notwithstanding thefact the rear of the train may vacate the section R-S and the trackrelay R may be picked up. Since the magnet 48 is deenergized and itsback contact 69 is closed when the track relay R is shunted, current issupplied to the signals SI and S2 for illumination of their respectivelamps. This circuit is traced from the B battery terminal over contact6I3Gl operated by the arm Kit, back contact 69 of magnet 48, wire 23,contacts i9'2ll and 2i-22 in parallel and thence to the lamps of thesignals S! and S2 as previously traced.

Since the cams 9 and it are now alternately opening and closing thecontacts i9-28 and 2l 22; the two lamps of each of the signals SI and S2are alternately flashed to exhibit a flashing signal to the highwayusers. When this train advances and enters the section TV and the trackrelay R is shunted, the field winding 7 of the oscillator CT is stillsupplied with current over the back contact E8 of the relay R and hencethe signals Si and S2 are flashed until such time as the rear of thetrain has advanced to the left of the highway H and vacated thesectionTV, since the magnet 43 is deenergized with relay R released. Inasmuchas the combined lengths of the sections ST and TV are equal to 2640feet, there is a 30 seconds operation of the highway signals before thetrain traveling at the. maximum speed of 60 miles per hour reaches theintersection. During the entire time the train occupies the sectionsS--T and T--V the ratchet gear 34 is rotated clockwise and the gear 39is proportioned and adjusted that it is effective to hold the shaft 5t,gear 39 and cam 53 in the normal position where the cam 53 is inengagement with the cam follower 59 of the arm 55, but it is not ofsufficient force to rotate the cam 53 against the weight of the arm'56at such time as the gear 39 is released and free to turn on the shaft36. Consequently, for a train traveling at the maximum speed of 60 milesper hour the cam :36 is rotated clockwise during the time the train isadvancing through the measuring section but with no movement of the arm56, the highway crossing signals are flashed for 30 seconds prior to thearrival of the train at the intersection, and 1 they continue to flashuntil the rear end of the train has passed beyond the highway andcleared the section TV. The cam id is restored to its normal positionimmediately upon the train entering the section ST due to the influenceof the counterweight ll, since the magnet 48 is now deenergized.

In the event a train approaches the highway H travelling at a speed lessthan the maximum speed, an operating interval different from the ,30seconds interval of operation obtained for the maximum speed iseffected, the interval decreasing from 30 seconds in proportion to thedecrease in the speed. I shall now assume a train traveling at 40 milesper hour approaches the highway.

The relay R isshunted and the oscillator CT is set into operation asthis train enters the measuring section RS the same as explained for thetrain traveling 60 miles per hour. The train traveling 4 .0 miles perhour consumes approximately 15 seconds in advancing through the sectionPt--S and entering the section S--T. During this 15 seconds the cam 40is rotated clockwise since the magnet iii is energized, and during thefirst seconds the cam 40 is rotated there is no upward movement of thearm 56 due to the circular surface of the cam as explained before,

but the surface of the cam it is so shaped that after the first 10seconds movement thereof the arm 56 is raised at a variable rate. Inother words, the cam 31! is so shaped that from each one secondoperation of the cam after the first 10 seconds period the arm 56 iscaused tomove a different angular movement about its pivot. 51, thisangular movement progressively increasing for a limited time. The resultof this upward movement of the arm 56 is to cause the contact 60 to moveaway from engagement with the stationary contact 5! During the upwardmovement of the arm 55 the spring 55 is effective to rotate the shaft 5tand cam 53 clockwise with the result that the cam follows along afterthe arm 56 maintains its engagement with the cam follower '59. The gear49 on the shaft 56 is now brought into mesh with the gear 39 but sincethe gear 39 is now free to turn on the shaft 3% it offers but slightopposition to the spring 55. When this train advances and enters thesection ST and shunts the track relay R the magnet 48 is deenergized aspreviously explained. The immediate efiect of deenergizing the magnet 53is to release the clutch member ll from the cam fill and to permit theclutch member M to move into frictional engagement with the gear 38'under the influence of spring ll. The cam id upon being released is atonce restored to its normal position due to the counterweight 1 i.Engagement of the gear 39 by the clutch member M is effective to causethe cam 55% to be rotated counterclockwise from the position to which ithad advanced along with the arm 56 back toward its normal position inopposition to the spring 55, the arm 56 follow ing the cam 53 due to theweight of its parts. As here shown, the surface of the cam 53 is soshaped as to cause a uniform rate of movement of the arm 56, that is,for each one second operation of the cam 53 the arm 56 is moved an equalangular distance about its pivot. The parts are so proportionedthat forthe train traveling at the speed of 40 miles per hour the arm is movedback to its normal position from the position to which it had beenadvanced by the cam 4t during the seconds the train was advancingthrough the measuring section in approximately seconds. Since the traintraveling 40 miles per hour requires approximately l5 seconds to travelthe 2640 feet between the entrance of the section S-T and the highway H,and since the arm 56 is not restored to its normal position where itcloses the contact til-61 for a period of 20 seconds, it follows thatthe highway crossing signals SI and S2 are flashed to warn highway usersfor a period of seconds before the train reaches the intersection.

Again, a train traveling 20 miles per hour consumes seconds in movingthrough the measuring section RS and entering the operating section S-T.The cam M! is rotated clockwise during thislSO seconds period and isthen released and allowed to swing back to its normal position. Whenthis train occupies the operating section S'I the cam 53 is rotatedcounterclockwise in response to operation of the oscillator CT asexplained for the previous train. The cams 40 and 53 are so shaped thatthe arm 56 is moved upward by the cam 46 during the 30 seconds the trainoccupies the measuring section to a position where it requiressubstantially 70 seconds operation of the cam 53 before the arm 56 isrestored to its normal position and the contact Bil-61 is closed. Sincea train of a speed of 20 miles per hour requires 90 seconds to advancethe 2640 feet from the entrance of the section S-T to the highway H, itfollows that 20 seconds operation of the signals SI and S2 is effectedbefore the train reaches the intersection.

The curve tam of Fig. 4 illustrates the time the highway crossingsignals are to be operated for the diiferent speeds up to the maximumspeed of 60 miles per hour, as arbitrarily assumed in the foregoingdescription. The curve trs illustrates the time consumed in themeasuring section R-S by trains of difierent speeds and which timedetermines the upward movement of the arm 56. The curve .tso illustratesthe time required by trains of different speeds to advance from theentrance of the operating section S--T to the intersection. The curvetszr is approximately the difference between the curve tsv and thearbitrary curve tzcu and illustrates the delay in setting the signalsinto operation after the train has passed the entrance of the section STto assure that the operating time of the signals before the trainreaches the intersection is in accordance with the curve tau. The curveto of Fig. 5 illustrates the relationship between the curves tits andtar of Fig. 4 and from which curve to the shape of the cam 40 isobtained.

. From an analysis of these curves and from the foregoing description ofthe operation of the apparatus at train speeds of 60, 40 and 20 milesper hour, it is apparent that with the apparatus constructed in themanner described the time measuring member (arm 56) is moved upwardabout its pivot at a variable rate and is restored at a uniform rate,and the highway crossing signals are set into operation at least 20seconds prior to the arrival of a train at the intersection when thespeed is 20 miles per hour and the operating time is increased for thehigher speeds until 'at the maximum speed of 60 miles per hour thesignals are set into operation 30 seconds prior to the arrival of thetrain at the intersection. As stated hereinbefore, my invention is notlimited to the specific speed limits, operating time and track layouthere described; The essential thing of my invention is that a timemeasuring member is moved away from a normal position at one rate duringa measuring period the duration of which is determined by the speed ofthe train, and the member is then returned to its normal position at asecond rate. In the form of the invention described hereinbefore, saidone rate is based upon the duration of the movement and upon apredetermined speed-time curve, and said second rate is based upon apredetermined speed-time curve, and the two rates are so proportionedthat the highway crossing signals are set into operation at least apredetermined minimum interval prior to the arrival of a slow speedtrain at the intersection, and are set into operation a predeterminedmaximum interval prior to the arrival of a train traveling at themaximum speed and the operating time for trains'of speeds intermediatethese two speeds is made to vary between the minimum and maximumintervals in proportion to the speed. It will be apparent, however, thatthe cam surfaces of the cams 40 and 53 may be shaped so that the rate ofmovement of arm 56 away from its normal position may be a uniform rateand the rate of movement of the arm back toward its normal position maybe something other than a uniform rate should it be so desired, andwarning periods of the highway crossing signal may be substantially aconstant interval prior to the arrival of a train at the intersectionfor all train speeds rather than the variable interval describedhereinbefore. I

Furthermore, with apparatus constructed in the manner here disclosed, asingle operating unit (oscillator CT) is effective to actuate the timemeasuring device in both its forward and backward movements and also tooperate the highway crossing signals.

In the event a train should stop or otherwise consume an unusually longtime in the measuring section R-S, the cam 40 would be rotated anunusual movement clockwise and the arm 56 would be raised to the reverseposition as illustratedby the dotted lines in Fig. 1. In this reverseposition of the arm 56 the contact finger 63 makes engagement with thecontact finger 65. Since the magnet 48 is energized while the trainoccupies the section R-S and its front contact 86 is closed, current issupplied from the B terminal of the current source over a simple circuitwhich includes contact 86, contact 63-65 and the winding of magnet 64and that magnet is energized andattracts the armature 62 on the arm 56with the result that the arm 56 is retained in this raised positionnotwithstanding the fact that cam 40 may be rotated clockwise on pastthe position where it engages the cam follower 58. The spring 55 iseffective to rotate the cam 53 and retain it in engagement with the camfollower 59 with the arm 56 in this reverse position, thegear 49 beingin mesh wtih the gear 39. At such time as the train which stopped in thesection R-S advances and moves into the section ST and shunts the trackrelay R the magnet 48 is deenergized, the cam 40 is released and assumesits normal position, and the arm 56 is released by the magnet 64 and isrestored to its normal position by the cam 53 in response to operationof the oscillator CT. In the event a train stops in the operatingsection ST and the arm 56 is restored to its normal position, prior tothe train vacating the section,

further operation of the cam 53 is avoided due to the portion 10 of thegear 49.

A check circuit is provided and the normal position of the timemeasuring device is checked. This check circuit extends from the Bbattery terminal over the contact 6!l6 l, front contact 18 of the magnet48 and thence to a signal 19. In the event the arm 56 fails to return toits normal position for any reason and the contact 60--6| is open, or iffor any reason-the magnet 48 is not energized and its front contact I8is not closed, the signal 19 is without current and assumes a stopposition in the usual manner for such signals. The signal 19 set at thestop position requires all trains to approach the highway H at arestricted speed.

By making the relay R one element of an interlocking relay, the otherelement of which is governed by traflic to the left of the highway H,the highway crossing signals SI and S2 may be governed in the usualmanner for trains moving only one form of apparatus embodying myinvention, it is understood that various changes and modifications maybe made therein within the scope of the appended claims without depart-'ing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: V r p 1. Incombination, a time measuring device including a ratchet gear and acircuit controlling element which element normally occupies a givenposition, operating means including a winding effective when energizedto actuate the ratchet gear in its forward direction, a first meansoperated by said gear and including a first cam effective to move saidelement away from the given position at a variable rate, a second meansoperated by said gear and including a second cam eiTective to restoretheelement toward the given position at a uniform rate, and

means for selectively governing said first and second means.

2. In combination; a time measuring device including an oscillatingarmature, a ratchet gear and a circuit controlling element, said ratchetgear operated in its forward direction in step with oscillations of thearmature and said element normally occupying a given position; a firstcontrol means operated by said gear and including a first cam effectiveto move said element away from the given position atone rate fective tomove the member away from said normal position for positioning themember in accordance with the time interval said cam is operated, asecond cam adaptable of operation by said unit when the winding isenergized and 'eiiective to restrain movement of said member by its biasandto permitthemember to gradually return to its normal position, clutchmeans including a clutch magnet to select said first or said second camfor operation by said unit ac cording as the magnet is energized or isdeenergized,'and controlmeans for controlling the energization of saidwinding and said magnet.

4. Time measuring means comprising, acircuit controlling contact membernormally occupying a given position, an operating unit including awinding and an armature which is oscillated at; a predetermined ratewhen the winding is energized, a ratchet gear connected withthe armaturefor rotationstep by step in response to oscillation of the armature, acam disposed when rotated to move said member away from said givenposition,'saidcam shaped for imparting a varied displacement to themember in accordance with the time interval the cam is rotated, meansincluding a clutch magnet to op- 'erati'vely connect the cam with saidgear when tact member, a first drive means efiective to move said memberin a forward direction in response to the rotation of said ratchet gear,a

second drive means efiective to govern the move ment of said member in abackward direction in response to rotation of said ratchet gear, aclutch magnet operative to render either the first drive means or thesecond drive means effective according as said magnet is energized or isdeen ergized, and control means for governing the energization of saidwinding and said magnet.

6. Time measuring means comprising, a circuit'controlling contact memberbiased to a normal position, an operating unit including a winding andan armature which is oscillated at a predetermined rate when the windingis energized, a ratchet gear connected with the armature for rotationstep by step in response to oscillation of the armature, a first camdisposed when operated to move said member away from said normalpositionfor imparting a displacement to the member in accordance with the timeinterval the cam is operated, means including a second cam to restrainmovement of said member by itsbias and to permit said member when saidsecond cam is operatedto return to the normal position at apredetermined rate, clutch means including a clutch magnet to connecteither said first cam or said second cam with said ratchet gear foroperation thereof according as said magnet is energized or isdeenergized, and control means for governing the energization of saidwinding and said magnet.

7. Time measuring means comprising, an operating unit including awinding and an armature which is oscillated at a predetermined rate whenthe winding is energized, a ratchet gear rigidly mounted, on a firstshaft, means operative to rotate the ratchet gear step by step in itsforward direction in response to oscillation of said armature, a firstdrive means including a first cam loosely mounted on said first shaft, asecond drive means including a second cam rigidly mounted on a secondshaft and a gear train having a drive gear loosely mounted on said firstshaft and a driven gear rigidly mounted on said second'shaft, clutchmeans including a clutch magnet V for selectively connecting either saidfirst cam or said drive gear with the ratchet gear according as saidmagnet is energizedor is'deenergized, a contact controlling arm biasedto a normal position and having two cam fol lowers one engaging each ofsaid cams for movement away from the normal position in response I trolmeans for governing the energization of said'winding and said magnet.

CRAWFORD E. STAPLES.

